fix(bash): sed replacement escaping, BSD portability, dead cleanup in update-agent-context.sh

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Summary

Three bugs in scripts/bash/update-agent-context.sh that cause silent failures on macOS and potential data corruption with special characters in project/technology names.

Bug 1: sed escaping targets wrong side (lines 318-320)

The escaping function escapes regex pattern characters ([, ., *, ^, $, +, {, }, |) but these variables are used as sed replacement strings, not patterns. In sed replacements, only two characters are special:

• & — inserts the entire matched pattern
• \ — escape character

Impact: A technology name containing & (e.g., "AT&T", "R&D") silently corrupts the agent context file. The & gets replaced with the entire matched text from the left side of the substitution.

Fix: Escape only & and \ in replacement strings. Also adds escaping for project_name which was used unescaped.

Bug 2: BSD sed newline insertion fails on macOS (lines 364-366)

# Current — fails silently on BSD sed (macOS)
newline=$(printf '\n')
sed -i.bak2 "s/\\\\n/${newline}/g" "$temp_file"

BSD sed does not support literal newlines in replacement strings via variable expansion. GNU sed (Linux) does. This means the \n → newline conversion silently fails on macOS, leaving literal \n sequences in the generated agent context files.

Fix: Replace with portable awk approach:

awk '{gsub(/\\n/,"\n")}1' "$temp_file" > "$temp_file.tmp" && mv "$temp_file.tmp" "$temp_file"

Bug 3: cleanup() removes non-existent files (lines 125-126)

rm -f /tmp/agent_update_*_$$
rm -f /tmp/manual_additions_$$

The script never creates files matching these patterns — all temp files use mktemp with random suffixes. The wildcard with $$ (PID) in /tmp is a code smell that could theoretically match unrelated files.

Fix: Remove the dead rm commands. Temp files from mktemp are cleaned up inline after use.

Testing

• bash -n syntax check passes
• Tested on macOS 15 (Darwin, BSD sed) — all three fixes verified

Related Issues

Fixes #154 — update-agent-context.sh seems to be failing on macOS
Fixes #293 — update-agent-context.sh script fails with sed expression errors
Related: #338 — Problems detected by shellcheck on the provided bash scripts